Vax2Muc reaches key milestones and advances new mucosal vaccine approaches

Developing vaccines that protect directly at mucosal surfaces remains one of the major challenges in infectious disease research. Vax2Muc is addressing this challenge by developing new vaccination strategies against Helicobacter pylori, a widespread bacterial infection linked to stomach inflammation, ulcers and gastric cancer.

Three years after the project started, the partners held another successful review meeting in September 2026 with the European Commission and external reviewers. During the meeting, the consortium reflected on the project’s second reporting period, in which they reached several important scientific and technical milestones and gained valuable new insights shaping the next phase of mucosal vaccine development.

A major manufacturing milestone

One of the period’s key achievements was successfully producing the project’s hybrid H. pylori vaccine antigen under Good Manufacturing Practice (GMP) conditions.

Two released drug substance batches are now available, providing high-quality material for further development and supporting the project’s long-term objective of progressing a lead vaccine candidate towards clinical evaluation.

Preclinical studies also confirmed that the first step of the vaccination strategy, an intramuscular injection of the vaccine antigen together with an adjuvant, triggers a strong immune response.

“The second reporting period has provided us with both important achievements and important lessons. We now have GMP-produced antigen available, strong evidence that the systemic vaccination step is immunogenic, and a much clearer understanding of what is needed to achieve effective mucosal protection.”, explains Verena Friedrich (TUM), Scientific Project Manager of the Vax2Muc project.

Adapting the strategy based on the data

An important objective of Vax2Muc is to strengthen immune protection directly at the gastrointestinal mucosa through a second vaccination step, known as the “mucosal pull”.

However, studies in mice and pigs showed that the originally selected mucosal delivery approach did not provide sufficient protection against H. pylori infection.

Rather than continuing with an approach that did not meet the required performance, the consortium activated alternatives already included in the project’s contingency planning. Two new mucosal delivery platforms have since been developed and are now being evaluated.

“This is exactly why several technological options were built into Vax2Muc from the start. Preclinical development is about testing assumptions rigorously and following the evidence. The findings allowed us to redirect our efforts towards alternative approaches with greater potential.”, explains Verena Friedrich.

New tools to understand mucosal immunity

The consortium also made progress in identifying measurable signs of an effective mucosal immune response.

Researchers identified a candidate immune biomarker associated with successful mucosal priming. Such biomarkers could help scientists compare different vaccine strategies more efficiently and support future decisions on which candidates should progress further in development.

This work forms part of the project’s broader effort to better understand the immune responses associated with protection against H. pylori.

Refining preclinical models

The second reporting period also generated important insights into the performance and limitations of the preclinical models used to evaluate vaccine candidates.

Naturally occurring background infections with related bacteria were found to complicate the interpretation of some experimental results. In response, the consortium is refining its preclinical strategy and moving toward models expected to provide a more controlled and reproducible setting for future vaccine studies.

These findings are helping the project to improve the quality and reliability of preclinical assessment and may also provide useful lessons for the wider development of vaccines against gastrointestinal pathogens.

Next steps

Vax2Muc now enters its next phase with GMP-grade vaccine antigen available, new mucosal delivery technologies under evaluation, improved immune monitoring tools and a refined preclinical strategy.

The consortium will focus on comparing and optimising the alternative delivery approaches and on identifying the most promising candidate for further development.

By combining vaccine manufacturing, innovative delivery technologies, immune monitoring and advanced preclinical models, Vax2Muc aims not only to advance an H. pylori vaccine, but also to generate knowledge and technologies that could support the development of mucosal vaccines against other gastrointestinal pathogens and contribute to the wider fight against antimicrobial resistance.